Ben of Six Apart explains why Six Apart has pledged support for Echo.  Unfortunately, his list of reasons are mostly resolvable technical complaints against RSS.  For example, Ben writes that Dublin Core elements are technically superior.  I'll agree with that.  If you would like to use Dublin Core, use it to supplement the existing elements, meaning add them alongside <pubDate> and <author>.  Even better, I would insert them under a single element.  That is how RSS is supposed to be extended.

While I understand his enthusiasm for Echo, I don't think attacking your bread-and-butter format in favor of a format that hasn't even been defined yet makes much business sense.  Just saying that the Echo is a good project and Six Apart will implement it if and when it becomes available should have been more than enough.

Ben, Echo is no excuse to stop enhancing and supporting interoperability of RSS.  Since I doubt this was your intention, please make this clear because your list of RSS problems seems to imply that RSS is a deadend for Six Apart.  If you need an MT template that uses Dublin Core without being funky, I can help you with that.